Adverse Infant and Maternal Outcomes Among Low-Risk Term Pregnancies Stratified by Race and Ethnicity.

OBJECTIVE: To assess whether racial and ethnic disparities in adverse infant and maternal outcomes exist among low-risk term pregnancies. METHODS: This population-based retrospective cohort study used U.S. vital statistics data from 2014 to 2017. Women with low-risk, nonanomalous singleton pregnancies who labored and delivered at 37-41 weeks of gestation were included and categorized by maternal race and ethnicity: non-Hispanic white (white), non-Hispanic black (black), Hispanic, and non-Hispanic Asian (Asian). Multivariable Poisson regression models were used to estimate the associations of composite neonatal adverse outcome (Apgar score less than 5 at 5 minutes, assisted ventilation for more than 6 hours, neonatal seizure, or neonatal death), infant mortality, and composite maternal adverse outcome (blood transfusion, admission to the intensive care unit, uterine rupture, or unplanned hysterectomy) with maternal race and ethnicity. RESULTS: Of 9,205,873 women included, 55.5% were white, 13.7% were black, 24.3% were Hispanic, and 6.5% were Asian. Risk for the composite neonatal adverse outcome was higher among neonates of black women (unadjusted relative risk [uRR] 1.16, 95% CI 1.13-1.18; adjusted relative risk [aRR] 1.07, 95% CI 1.05-1.10), and lower for neonates of Hispanic and Asian women compared with neonates of white women. A similar pattern of disparity was observed for infant mortality; the risk for infants of black women was significantly increased (uRR 1.89, 95% CI 1.81-1.98; aRR 1.33, 95% CI 1.26-1.39). For the composite maternal adverse outcome, the risk was highest for Asian mothers (uRR 1.09, 95% CI 1.03-1.14; aRR 1.12, 95% CI 1.06-1.18), lowest for Hispanic mothers, and similar for black mothers when compared with white mothers after adjustment for confounders. CONCLUSION: Among low-risk term pregnancies, the risk for adverse outcomes varied by maternal race and ethnicity. Infants of black women were at the highest risk for neonatal morbidity and infant mortality, and Asian mothers were most likely to experience maternal adverse outcomes.